The present invention relates generally to boxes, and more specifically to boxes for storing, mailing, or shipping various articles.
Boxes for storing, mailing, or shipping goods have been known in the prior art. In their simplest embodiment, those boxes comprise several body panels forming the sides of the box, and a pair of end panels connected to one or more of the side panels to close the ends of the box. The end panels usually are secured to the side panels by adhesive tape or the like, to close the box. The end panels may terminate with folded flap portions which are inserted beneath one of the body panels to provide a self-securing closure, but such conventional closures usually are less secure than taping shut the box panels. The conventional box may also feature a plurality of overlapping panels which are secured to each other by means of adhesive to form integral end panels. U.S. Pat. No. 3,512,823 is an example of such a box structure.
In order to provide a somewhat more secure closure mechanism, end panels of boxes have been provided with a tabbed portion along the distal edge thereof. These tabbed portions are simply inserted through a mating slit of substantially the same length located on a side panel of the box, the tab after insertion through the slit being glued to the exterior surface of the side panel. U.S. Pat. Nos. 916,503 to Thompson and 4,752,028 to Ogura disclose such a structure.
In the alternative, such tabs have been provided with leading edges which are longer in dimension than the length of the mating slit so that the tab and side panel around the perimeter of the mating slit provide interlocking abutment surfaces, as shown in U.S. Pat. Nos. 2,834,531 to Struble; 2,028,677 to Lupton; 1,530,644 to Blandford; and 4,516,718 to Forbes, Jr. The end portions of such an elongated tab must be folded upon the center portion thereof to permit inserting the tab through the slit, whereupon the elasticity or "memory" of the corrugated board causes the end portions to revert towards their original portion, thereby providing the interlock. However, the leading edge of the locking tabs taught by these box configurations either protrudes through the slit so that it is exposed outside the box or else only provides marginal interlocking structure. Therefore, the locking tabs may be easily unlocked from engagement with the slit of the box and the top panel removed without leaving any visible evidence of tampering.
Some box manufacturers, therefore, have resorted to a locking tab arrangement whereby the tab is affixed to a box panel so that the tab is inserted into the box through the slit, whereupon the reverted locking tab is inaccessible. The only means of opening the box end panel, therefore, is to tear or sever the locking tab from where that tab joins the side panel of the box, thereby providing visible evidence of tampering. The profile of such panels may be rectangular (U.S. Pat. Nos. 4,830,270 to Holmes; 3,949,931 to Hall; 1,470,141 to Bryson; 1,108,464 to Morey; and 636,806 to Johnstone), crescent-shaped (U.S. Pat. No. 3,451,535), or slightly tapered, although still with a flat leading edge (U.S. Pat. Nos. 3,462,066 to Farquhar; and 4,471,902 to Skaggs). However, these tabs provide a completely straight leading edge when the end portions of the tab are folded onto the center portion thereof, thereby making insertion through the narrow slit difficult. Moreover, the double layered leading edge of the folded tab inevitably becomes slightly separated during the insertion stage, once again providing undesirable abutment between the tab and the slit prior to inserting the tab through the slit.
U.S. Pat. No. 5,350,108, assigned to the owner of the present application, discloses an improved self-locking box. That patent describes a box having at least one panel secured to another panel by a locking tab and slot assembly, so that the secured panel cannot be opened without leaving visible evidence of tampering. To accomplish that locking, the box of the '108 patent includes an end panel having a flap extending into the box. The slot is located in the flap. The locking tab is foldable to fit through the slot, and a terminal portion of the locking tab engages a surface on the interior of the box so as to prevent withdrawing the locking tab. However, there remains at least some possibility that a box with the self-locking structure shown in the '108 patent could be nondestructively opened by a determined person who knew the internal construction of the box and had the time, the tools, and a measure of luck to defeat the lock structure.